1. Field of the Invention
This invention relates generally to the field of integrated circuit manufacturing and, more particularly, to a method for forming a rough polysilicon film.
2. Description of the Related Art
In semiconductor manufacturing, it is sometimes desirable to deposit polysilicon film on a substrate in such a way that rough polysilicon results. In dynamic random access memory (DRAM) technologies, for instance, it may be desirable to manufacture a memory cell capacitor using rough polysilicon.
A capacitor having a given lateral area manufactured with a rough polysilicon plate will have a higher capacitance than a capacitor of having the same lateral area manufactured with a smooth plate. The rough polysilicon capacitor has a larger effective dielectric surface area due to the folding of the capacitor dielectric over the rough film. When used in a DRAM memory cell, the larger dielectric surface area increases the memory cell's capacitance and improves the cell's charge storage characteristics, thereby improving product performance.
Unfortunately, the use of traditional manufacturing methods to produce rough polysilicon have been generally unsatisfactory because of the widely varying roughness they produce. The instant process results in a more reliable rough polysilicon film that is more easily controlled. Moreover, because the instant process uses etchants and techniques common to the semiconductor industry, this improved process can be readily integrated into modern day manufacturing flows.